The present invention relates to a bipolar voltage to frequency converter for use in applications such as chemical chromatography, absorption meters and data acquisition systems.
A voltage to frequency converter is commonly used to convert analog electronic signals representing some quantity of interest (such as voltage amplitude) to digital electronic signals coded to represent numerical values. Such converters are used throughout the electronic industry.
Prior art approaches have in general utilized a unipolar voltage to frequency converter. The prior art, however, present some problems in electronic applications in that such voltage to frequency converters cannot output negative numbers, since there is only one frequency output line with no sign (i.e., whether the frequency is positive or negative).
Negative inputs are handled by offsetting the input (adding a fixed voltage that is summed with the signal). Thus, when an input signal swings negative, the output swings from the offset value to a smaller positive value. Equivalent offset must be subtracted digitally by some means in order to produce negative numerical values. The offset generator is a source of noise and drift, which can present errors in the desired output.